Do Estrogen and Alendronate Improve Metaphyseal Fracture Healing When Applied as Osteoporosis Prophylaxis?

Osteoporosis is accompanied by predominantly metaphyseal fractures with a delayed and qualitatively reduced healing process. This study addressed the question of whether fracture healing in the context of osteoporosis prophylaxis is improved with estrogen (E) or alendronate (ALN). Thirty-six ovariectomized and 12 sham-operated 12-week-old rats received soy-free (osteoporotic C, sham), E-, or ALN- supplemented diets. After 10 weeks, a metaphyseal tibia osteotomy and standardized T-plate fixation were performed. After a 5-week healing process, the fracture callus was evaluated qualitatively by biomechanical bending test and quantitatively in microradiographic sections. The time course of callus formation was examined using fluorochrome-labeled histological sections. Administration of E improved the biomechanical properties of callus (stiffness [N/mm]: sham: 110.2 ± 76.07, C: 41.28 ± 33.70, E: 85.72 ± 47.24, ALN: 72.07 ± 34.68). The resistance to microfracturing seen in E-treated animals was significantly enhanced and even superior to sham (yield load [N] sham: 27.44 ± 9.72, C: 21.04 ± 12.47, E: 42.85 ± 13.74 ∆ , ALN: 25.28 ± 6.4 · ) (* P